1. Field of the Invention
The present invention relates to floss material, and particularly to floss made from expanded polytetrafluoroethylene (PTFE) fibers.
2. Description of Related Art
Since the development of the invention of U.S. Pat. No. 3,953,566 to Gore, flexible fibers made from expanded polytetrafluoroethylene (PTFE) have been used for a variety of purposes, including as a dental floss to clean between teeth. U.S. Pat. No. 4,776,358 to Lorch discloses one such use of an expanded PTFE floss material whereby the floss is folded upon itself to contain active agents. Use of waxed coated expanded PTFE fibers is taught in a number of other patents, including U.S. Pat. Nos. 5,033,488 and 5,209,251 to Curtis et al. U.S. Pat. No. 5,220,932 to Blass discloses use of a non-porous PTFE floss material. Presently there are a number of commercially available expanded PTFE flosses, including those sold under the trademarks GLIDE.RTM. by W. L. Gore & Associates, Inc., COLGATE PRECISION.RTM. by Colgate Palmolive Company, and EASY-SLIDE by Johnson & Johnson Consumer Products, Inc.
Expanded PTFE flosses have a number of advantages over conventional nylon flosses, including resistance to shredding (and its accompanying sticking of fiber shreds between teeth) and high lubricity. Although existing expanded PTFE flosses are resistant to shredding, unfortunately they still experience a degree of fibrillation. Fibrillation in dental floss is distinguished from shredding in that shredding is considered the breaking off of individual strands of the fiber between teeth, whereas, fibrillation is the splitting of the original fiber to form separate continuous fibers. Both fibrillation and shredding are not desired in a dental floss product. Other problems with expanded PTFE materials is that they tend to be difficult to process and they can have a number of structural problems. For instance, unlike conventional nylon floss that is formed from multiple strands twisted into a fiber with uniform dimensions, expanded PTFE floss materials have been formed from a thin, flat tape slit into single filament strands and then folded prior to the spooling process. This has made expanded PTFE material difficult to control during processing, resulting in a floss with inconsistent width and thickness dimensions along its length. Another concern with expanded PTFE material is that its strength and thinness often produces a floss material that can cut into a user's hands or provide an uncomfortable surface against a user's gums. Finally, it has been believed that leaving thin edges of expanded PTFE floss fiber exposed during flossing may lead to some limited fibrillation.
To address these concerns, commercially available expanded PTFE flosses have one or both of its edges folded upon the floss fiber to increase the thickness of the floss. This process produces a thicker floss without exposed edges, reducing handling and fibrillation problems. Regretfully, such floss material remains difficult to process while maintaining uniform width and thickness dimensions. Furthermore, the folded floss has a tendency to unfold during use, as well as during processing, resulting in a floss material with varying thickness and varying width. Inconsistent thickness is of particular concern since the thickness dimension is believed to be critical for allowing the floss to fill the gap between the teeth for optimal cleaning. Finally, the "feel" of the available PTFE floss material is still wanting both when held by the user and when flossing between teeth.
Accordingly, it is a primary purpose of the present invention to provide an expanded PTFE floss material of uniform dimensions that can be more readily processed.
It is a further purpose of the present invention to provide an expanded PTFE floss material that is more "gripable" and easily handled and used than existing expanded PTFE flosses.
It is still another purpose of the present invention to provide an expanded PTFE floss material that is not folded during processing.
It is yet another purpose of the present invention to provide an expanded PTFE floss with properties presently not available with existing floss materials.
These and other purposes of the present invention will become evident from review of the following specification.